Commutator grinder

ABSTRACT

A grindstone or like block of abrasive material is affixed at the lower end of a first support rod slidably received in a vertical sleeve. A second support rod coupled to the sleeve at a right angle thereto is also slidably received in a hollow offset arm at the upper end of an upright standard. An electromagnet is clamped to the standard for releasably mounting the commutator grinder on a desired commutator machine. The commutator grinder is further equipped with an infeed mechanism and a traverse feed mechanism which enable the grindstone or the like to be fed toward and in the traverse direction of the work. The infeed mechanism comprises a handle, worm gearing, and a feed rod screwthreadedly received in a hollow formed axially of the first support rod, such that the rotation imparted from the handle to the feed rod via the worm gearing is translated into the up-anddown motion of the first support rod relative to the sleeve. The traverse feed mechanism also comprises a handle and a feed rod screw-threadedly received in a hollow formed axially of the second support rod, the rotation of the second mentioned feed rod being likewise translated into the back-and-forth motion of the second support rod relative to the offset arm.

[ 1 Nov. 26, 1974 United States Patent 1 Ogura ABSTRACT COMMUTATOR GRINDER [75] Inventor:

Taketoshi Ogura, Tokyo, Japan Assignee: Sanwa Kiko Kabushiki Kaisha, A grindstone or like block of abrasive material is af- Tokyo, Japan fixed at the lower end of a first support rod slidably received in a vertical sleeve. A second support rod coupled to the sleeve at a right angle thereto is also slidably received in a hollow offset arm at the upper [22] Filed: Nov. 9, 1973 21 Appl. No.: 414,187

end of an upright standard. An electromagnet is clamped to the standard for releasably mounting the [30] Foreign Application Priority Data June 4, 1973 commutator grinder on a desired commutator machine. The commutator grinder is further equipped withan infeed mechanism and a traverse feed mechanism which enable the grindstone or the like to be fed Int. B24b 19/26 t ward and in the traverse direction of the work. The infeed mechanism comprises a handle, worm gearing,

[58] Field of Search 51/244, 241 S, 241 R and a feed rod screw-threadedly received in a hollow formed axially of the first support rod, such that the rotation imparted from the handle to the feed rod via the worm gearing is translated into the up-and-down motion of the first support rod relative to the sleeve. 51/244 The traverse feed mechanism also comprises a handle and a feed rod screw-threadedly received in a hollow 51/35 formed axially of the second support rod, the rotation 5 1/ 125 of the second mentioned feed rod being likewise translated into the back-and-forth motion of the second support rod relative to the offset arm. a

References Cited UNITED STATES PATENTS 3/1888 Tittle 9/1919 Decker 12/1930 Newbrough. 12/1934 Gottlieb.

9/1952 Indge 3/1955 Porter........ 6/1956 Muehlingm... 6/1972 McDowell.......,......,............,

l l l 2 2 2 3 6 Claims, 5 Drawing Figures Primary Examiner-Donald G. Kelly Assistant Examiner-Margaret Joyce Attorney, Agent, or Firm-Toren, McGeady and Stanger PATENH, 25w 2 61974 3, 849 sum ear 3 946 FlG.2

COMMUTATOR GRINDER BACKGROUND OF THE INVENTION This invention relates generally to grinding machines, and more specifically to a commutator grinder to be mounted directly on a commutator machine such for example as a motor or generator for reconditioning the surface of the commutator in situ, without removing the armature therefrom. As is well known, the faces of the commutators in electric motors, generators and the like become inevitably covered with oxide films after prolonged hours of use and become further roughened or otherwise damaged due to excessive load or to sliding contact with the brushes. Moreover, since the mica insulation between the copper commutator segments of the usual commutator machines is generally more resistant to the wear of the brushes than the segments, there occurs a phenomenon known in the art as high mica by which is meant the mica projecting from between the worn copper segments. The commutators thus become gradually unable to perform their functions. It is therefore necessary to recondition the commutator faces at regular time intervals.

However, such reconditioning of the commutator faces has hitherto called for the manual labor of highly skilled workers. Alternatively, the armatures of the commutator machines have been removed therefrom for first machining the commutators on a lathe and then finishing them by the usual cylindrical grinding machine. Although there have more recently been developed portable grinders adapted specifically to recondition the commutator faces without removing the armatures from the commutator machines, such prior art commutator grinders have almost unexceptionally been unnecessarily complex and expensive in construction and seem to have not yet found universal acceptance.

SUMMARY OF THE INVENTION In view of the noted deficiencies of the prior art, it is an object of this invention to provide a commutator grinder of simple and inexpensive construction which is to be mounted directly on a commutator machine for reconditioning the surface of the commutator in situ.

Another object of the inventionis to provide a commutator grinder which can be easily mounted in the most convenient position on a commutator machine and in which a grindstone or like block of abrasive material can also be easily located in a desired starting position on the commutator to be ground thereby.

Still another object of the invention is to provide a commutator grinder including both an infeed mechanism and a traverse feed mechanism of very simple construction which can be operated manually to enable the grindstone or the like to uniformly recondition the commutator face.

A further object of the invention is to provide a commutator grinder in which the infeedmechanism includes a reduction gear adapted to impart a highly precise infeeding movement to the grindstone or the like.

With these objects in view and the other objects hereinafter set forth, this invention provides a commutator grinder which, stated in its perhaps broadest aspects, includes a first support rod carrying a block of abrasive material at its lower end and slidably received in a vertical sleeve. A second support rod also slidably re-.

ceived in a horizontally disposed hollow ann has its exposed end coupled to the sleeve at a right angle thereto, and the hollow arm itself is coupled to the upper end of an upright standard having electromagnet means adapted to releasably attach the commutator grinder to a desired part of a commutator machine casing. The desired infeeding and traversing movements of the abrasive block are provided by an infeed mechanism which causes the first support rod to move up and down relative to the sleeve and by a traverse feed mechanism which causes the second support rod to move back and forth relative to the hollow arm.

Typically, the infeed mechanism comprises a first handle, a first feed rod screw-threadedly received in an' axial bore of the first support rod, and reduction gear means such as worm gearing adapted to transmit the rotation of the first handle to the first feed rod at greatly reduced speed. The rotation of the first feed rod is then. translated into the linear motion of the first support rod relative to the sleeve. It will be apparent that the abrasive block at the lower end of the first support rod can be fed in the traverse direction of the work if the second support rod coupled to the sleeve is moved back and forth relative to the hollow arm. To this end,

the traverse feed mechanism comprises a second feed rod screw-threadedly received in an axial bore of the second support rod, and a second handle mounted directly on the second feed rod. No reduction gearing is usually required for causing the traversing movement of the abrasive block.

The features which are believed to be novel and characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its construction and mode of operation, together with the further objects and advantages thereof, will be best understood from the following description of a preferred embodiment illustrated in the accompanying drawings in which like referencenumerals denote like parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a perspective view of a commutator grinder constructed by way of a preferred. embodiment of this invention;

FIG. 2 is an end elevational view, partly in vertical section, showing in more detail the infeed mechanism and the means for supporting a grindstone or like block of abrasive material in the commutator grinder of FIG.

FIG. 3 is a partial vertical sectional view of the worm gearing used in the infeed mechanism of FIG. 2;

FIG. 4 is a partial side elevational view, partly in vertical section, showing in more detail the traverse feed mechanism in the commutator grinder of FIG. 1; and

FIG. 5 is a side elevational view showing the commutator grinder of FIG. 1 as used for reconditioning the commutator face of an electric motor illustrated in partial vertical section in the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in FIG. I, the commutator grinder illustrated therein by way of a preferred embodiment of the invention includes a grindstone or a similar block of abrasive material 10 affixed at the lower end of a first support rod 11. This first support rod is slidably received in a sleeve 12, as best illustrated in FIG. 2, in such a manner that by the manual turn of an infeed handle 13, the first support rod 11 together with the abrasive block sup ported at its lower end is movable up and down relative to the sleeve. The abrasive block 10, the first support rod 11 and other related parts hereinafter set forth in detail are supported by an offset arm 14 clamped at 15 to the upper end of an upright standard 16, in such a fashion that the abrasive block is movable toward and away from the standard by the manual turn of a traverse feed handle 17. Electromagnet means 18 of any known or suitable construction is clamped at 19 to the standard 16 for removably attaching the commutator grinder to the casing of a desired commutator machine. The position of the clamp 19 and therefore of the electromagnet means 18 relative to the standard 16 is variable by loosening bolts 20 on the clamp 19.

FIG. 2 illustrates the details of the means for securing the abrasive block 10 to the bottom end of the first support rod 11 and of the infeed mechanism for pressing the abrasive block against the work in a direction normal to that of the axis of its rotation. The abrasive block 10 is fixedly supported between a pair of plate members 21 which are bolted at 22 to a fixture 23 at the bottom end of the first support rod 11. A piece of wood 24 is interposed between the abrasive block 10 and the fixture 23 in order to cushion vibrations which may be produced during grinding operation. If the plate members 21 are formed of electrically insulating material, they will serve, in cooperation with the piece of wood 24, to electrically insulate the rest of the grinder machine from the commutator being ground thereby. It will be apparent that the abrasive block 10 should also be formed of electrically insulating material. The abrasive block when worn or damaged can be easily replaced by simple manipulation of the bolts 22.

The aforesaid infeed mechanism according to the invention makes use of reduction gear means in view of the fact that the abrasive block 10 must be fed into the work very slowly and in a manner permitting fine adjustment of the degree of such infeeding motion. In this particular embodiment of the invention, the reduction gear means takes the form of worm gearing comprising a worm 25 fixedly mounted on a revolvable shaft 26 at one end of which is secured the above mentioned infeed handle 13, and a worm wheel 27 keyed at 28 to a first feed rod 29 which is rotatably supported as by conical roller bearings 30 in coaxial relationship to the first support rod 11. The worm 25 and the worm wheel 27 are in gear as shown in FIG. 3. The lower portion of the first feed rod 29 is received in a hollow 31 formed axially of the first support rod 11, and square threads formed at 32 on the first feed are mated with internal threads 33 formed correspondingly on the inside of the first support rod.

Although the first support rod 1 l is slidably received in the sleeve 12 as previously mentioned, the rotation of the former relative to the latter is prevented by means of a sliding key 34, such that the bidirectional rotation of the first feed rod 29 on its axis is translated into the up-and-down motion of the first support rod within the sleeve. Hence, if it is assumed that the worm wheel 27 makes one complete revolution for each 80 complete revolutions of the worm 25, and that the lead of the mating square threads is 16 millimeters, then the abrasive block 10 will be fed only 0.2 millimeter by each complete revolution of the infeed handle 13.

FIG. 4 illustrates in detail the traverse feed mechanism for feeding the abrasive block 10 in a traverse direction of the commutator being ground thereby. The traverse feed mechanism includes the aforesaid offset arm 14 clamped at 15 to the upper end of the upright standard 16. It will be seen that the length of this offset arm projecting from the clamp 15 is adjustable within predetermined limits by loosening bolts 35 on the clamp. The arm 14 is hollowed axially therethrough to slidably receive a second support rod 36, which is also hollowed axially to receive a second feed rod 37 screwthreaded at 38 to mate with internal screw threads 39 cut on the inside of the second support rod 36.

The second feed rod 37 is rotatably supported by the offset arm 14 via a radial ball bearing 40, and the traverse feed handle 17 is fixedly mounted on one end of the second feed rod projecting out of the arm 14. Since a key 41 formed on the outside of the second support rod 36 is slidably fitted in a keyway formed longitudinally on the inside of the offset arm 14, the rotation of the traverse feed handle 17 and hence of the second feed rod 37 is translated into the linear motion of the second support rod 36 relative to the arm. One end of the second support rod 36 exposed from the offset arm 14 is securely coupled through a fixture 42 to a frame 43 supporting the sleeve 12, as best illustrated in FIG.

FIG. 5 illustrates a mode of use of the preferred embodiment of the invention set forth in the foregoing. The commutator grinder according to the invention is supported in position by the electromagnet means 18 which is attached to an end plate 44 of a desired commutator machine such, for example, as a motor 45. The height of the standard 16 above the electromagnet means 18 may be adjusted as required by loosening the bolts 20 on the clamp 19. The traverse feed handle 17 is then turned to cause the abrasive block 10 to move traversely of the commutator 46 mounted within the motor 45 until the abrasive block is located right above the commutator. Thereafter the infeed handle 13 is turned to cause the abrasive block 10 to descend into contact with the commutator 46 as seen in the drawing.

With the commutator grinder thus made ready for operation, an electric current is delivered in the usual manner to the motor 45, either continuously or at suitable time intervals, to set its armature in rotation. While the commutator surface is being thus ground by the abrasive block 10, the traverse feed handle 17 may be turned in both directions thereby imparting a traversing movement to the abrasive block 10 to ensure uniform grinding of the entire surface of the commutator 46. The infeed handle 13 may also be turned as required in the predetermined direction to cause descent of the abrasive block into the commutator and hence to provide the required grinding pressure.

While the various objects of this invention, either explicitly stated or otherwise set forth, are believed to be fully accomplished by the preferred embodiment disclosed herein, it will also be understood that such specifically recited embodiment is subject to various modifications or changes within the usual knowledge of those skilled in the art. Further, in some instances, some features of the invention may be employed without the corresponding use of other features. It is therefore appropriate that the invention be construed broadly and in a manner consistent with the fair meaning or proper scope of the claims appended hereto.

What is claimed is:

1. A commutator grinder to be mounted on a commutator machine for reconditioning the surface of the commutator in situ, comprising in combination:

a block of abrasive material;

a first support rod carrying said block of abrasive material at its lower end;

a sleeve adapted to slidably receive said first support rod;

infeed means for moving said first support rod up and down relative to said sleeve in order to infeed said block of abrasive material with respect to the commutator;

a second support rod coupled to said sleeve at a right angle thereto;

a hollow arm adapted to slidably receive said second support rod;

traverse feed means for moving said second support rod back and forth relative to said arm in order to impart traversing motion to said block of abrasive material with respect to the commutator; and

a standard having electromagnet means adapted to releasably attach the commutator grinder to the commutator machine, said arm being coupled to the upper end of said standard at a right angle thereto.

2. The commutator grinder as set forth in claim 1, wherein said infeed means comprises:

a key adapted to permit said first support rod to move only linearly relative to said sleeve;

a feed rod received in a hollow formed axially of said on said first support rod;

reduction gear means associated with said feed rod; and a handle adapted to impart rotation to said feed rod via said reduction gear means, the rotation of said feed rod being translated into the linear motion of said first support rod relative to said sleeve.

3. The commutator grinder as set forth in claim 2,

wherein said reduction gear means comprises:

a worm wheel fixedly mounted on said feed rod for simultaneous rotation therewith; and

a worm in mesh with said worm wheel, said worm being fixedly mounted on a shaft to which is secured said handle.

4. The commutator grinder as set forth in claim 1,

wherein said traverse feed means comprises:

wherein said arm is coupled to the upper end of said standard by means of a clamp, said clamp being loosenable to vary the length of the portion of said arm projecting therefrom.

6. The commutator grinder as set forth in claim 1,

wherein said electromagnet means is coupled to said standard by means of a clamp, said clamp being loosenfirst support rod, said feed rod being externally able to vary the height of said standard.

screw threaded to mate with internal screw threads 

1. A commutator grinder to be mounted on a commutator machine for reconditioning the surface of the commutator in situ, comprising in combination: a block of abrasive material; a first support rod carrying said block of abrasive material at its lower end; a sleeve adapted to slidably receive said first support rod; infeed means for moving said first support rod up and down relative to said slEeve in order to infeed said block of abrasive material with respect to the commutator; a second support rod coupled to said sleeve at a right angle thereto; a hollow arm adapted to slidably receive said second support rod; traverse feed means for moving said second support rod back and forth relative to said arm in order to impart traversing motion to said block of abrasive material with respect to the commutator; and a standard having electromagnet means adapted to releasably attach the commutator grinder to the commutator machine, said arm being coupled to the upper end of said standard at a right angle thereto.
 2. The commutator grinder as set forth in claim 1, wherein said infeed means comprises: a key adapted to permit said first support rod to move only linearly relative to said sleeve; a feed rod received in a hollow formed axially of said first support rod, said feed rod being externally screw threaded to mate with internal screw threads on said first support rod; reduction gear means associated with said feed rod; and a handle adapted to impart rotation to said feed rod via said reduction gear means, the rotation of said feed rod being translated into the linear motion of said first support rod relative to said sleeve.
 3. The commutator grinder as set forth in claim 2, wherein said reduction gear means comprises: a worm wheel fixedly mounted on said feed rod for simultaneous rotation therewith; and a worm in mesh with said worm wheel, said worm being fixedly mounted on a shaft to which is secured said handle.
 4. The commutator grinder as set forth in claim 1, wherein said traverse feed means comprises: a key adapted to permit said second support rod to move only linearly relative to said arm; a feed rod received in a hollow formed axially of said second support rod, said feed rod being externally screw threaded to mate with internal screw threads on said second support rod; and a handle adapted to rotate said feed rod to cause linear motion of said second support rod relative to said arm.
 5. The commutator grinder as set forth in claim 1, wherein said arm is coupled to the upper end of said standard by means of a clamp, said clamp being loosenable to vary the length of the portion of said arm projecting therefrom.
 6. The commutator grinder as set forth in claim 1, wherein said electromagnet means is coupled to said standard by means of a clamp, said clamp being loosenable to vary the height of said standard. 